The present invention relates in general to endoscopic harvesting of blood vessels, and, more specifically, to avoiding buildup of debris on a endoscopic cutting tool used to severe branches from a blood vessel being harvested.
The present invention relates to the harvesting of blood vessels and, more particularly, to methods and apparatus for endoscopic dissection and retraction of sections of blood vessels, such as saphenous veins, for use as a coronary artery bypass graft.
In connection with coronary artery bypass grafting (CABG), a blood vessel or vessel section, such as an artery or vein, is “harvested” (i.e., removed) from its natural location in a patient's body and to use it elsewhere in the body. In CABG surgery, the blood vessel is used to form a bypass between an arterial blood source and the coronary artery that is to be bypassed. Among the preferred sources for the vessel to be used as the bypass graft are the saphenous veins in the legs and the radial artery in the arms.
Endoscopic surgical procedures for harvesting a section of a vein (e.g., the saphenous vein) subcutaneously have been developed in order to avoid disadvantages and potential complications of harvesting through a continuous incision (e.g., along the leg) for the full length of the desired vein section in order to provide adequate exposure for visualizing the vein and for introducing surgical instruments to sever, cauterize and ligate the tissue and side branches of the vein. One such minimally-invasive technique employs a small incision for locating the desired vein and for introducing one or more endoscopic harvesting devices. Primary dissection occurs by introduction of a dissecting instrument through the incision to create a working space and separate the vein from the surrounding tissue. Then a cutting instrument is introduced into the working space to severe the blood vessel from the connective tissue surrounding the section to be harvested and any side branches of the blood vessel. The branches may be clipped and/or cauterized.
In one typical procedure, the endoscopic entry site is located near the midpoint of the vessel being harvested, with dissection and cutting of branches proceeding in both directions along the vessel from the entry site. In order to remove the desired section of the blood vessel, a second small incision, or stab wound, is made at one end thereof and the blood vessel section is ligated. A third small incision is made at the other end of the blood vessel section which is then ligated, thereby allowing the desired section to be completely removed through the first incision. Alternatively, only the first two incisions may be necessary if the length of the endoscopic device is sufficient to obtain the desired length of the blood vessel while working in only one direction along the vessel from the entry point.
An example of a commercially available product for performing the endoscopic vein harvesting described above is the VirtuoSaph™ Endoscopic Vein Harvesting System from Terumo Cardiovascular Systems Corporation of Ann Arbor, Mich. Endoscopic vein harvesting systems are also shown in U.S. Pat. No. 6,660,016 to Lindsay and U.S. patent application publication 2005/0159764A1 in the name of Kasahara et al, both of which are incorporated herein by reference in their entirety.
In the VirtuoSaph™ System and Kasahara et al, the cutting tool for severing and cauterizing branches has the form of a V-cutter wherein a V-shaped tip at the distal end of the cutter guides a branch to be cut into a longitudinal slit. Electrodes adjacent the slit are electrically energized with a high frequency voltage in order to sever and cauterize the branch by extreme heating. During the process of cutting and cauterizing the many branches coming from the vein being harvested, fat, connective tissue, burnt residue, and other body material builds-up on the V-cutter thereby reducing the effectiveness of the cutting operation. The amount of debris build-up depends in part on the physiology of the patient. With excessive build-up, known systems have required medical personnel to remove the harvesting rod from the patient in order to clear away this debris so that effective cutting can be resumed. Such removal undesirably complicates the procedure and prolongs it. Thus, it would be desirable to reduce patient risks by avoiding the need to remove the harvesting rod in order to clear debris from the area of the longitudinal slit in the V-cutter.